Power supply system for a vacuum pump and vacuum pump

ABSTRACT

A power supply system for vacuum pump comprising a power supply means to supply electrical energy to the vacuum pump for operation and energy storage means connected to the vacuum pump to store energy produced by the vacuum pump during ramp-down of the vacuum pump.

CROSS-REFERENCE OF RELATED APPLICATION

This application is a Section 371 National Stage Application of International Application No. PCT/GB2018/051905, filed Jul. 5, 2018, and published as WO 2019/008371 A1 on Jan. 10, 2019, the content of which is hereby incorporated by reference in its entirety and which claims priority of British Application No. 1710987.7, filed Jul. 7, 2017.

FIELD

The present invention relates to a power supply system for a vacuum pump and a vacuum pump with such a power supply system.

BACKGROUND

Certain users of vacuum pumps require rapid cycling of their vacuum pump from zero rotational speed to full rotational speed during ramp-up, perform their analysis and then stop the pump from full speed to rest during ramp-down. As a result of several factors, turbo pump ramp-up times (from rest to full speed) can be several minutes. Equally, deceleration times (full speed to rest) can take several minutes. This can create inconvenience for customers who can only operate their processes when the pump achieves, for example, full rotational speed.

The long ramp--up time is due to the limited torque delivered by the motor but can also be influenced by the capacity of the power supply selected by the customer. For example, a certain pump may be rated at 100W, but a customer may select a 50W power supply due to cost or size constraints. This may be a sufficient power for full speed running, but the penalty is slow ramp-up times. Additionally, there may be system power/budget constraints or constraints due to economic reasons. Therefore, there is a balance to strike between power supply capacity and required system ramp time.

The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations solve any or all disadvantages noted in the background.

SUMMARY

Thus, it is an object of the present invention to provide a power supply to improve cycling times.

This technical problem is solved by a power supply system in accordance with claim 1, a vacuum pump in accordance with claim 6 and also by a method for shutting-down a vacuum pump in accordance with claim 7 and a method for starting-up a vacuum pump in accordance with claim 8.

The inventive power supply system for a vacuum pump comprises a power supply means to supply electrical energy to the vacuum pump for operation. With the power supply means an energy storage means is connected, whereby the energy storage means is configured to store energy produced by the vacuum pump during ramp-down of the vacuum pump. Thereby the energy storage means can be connected to the power supply means via a motor controller. Thus, the energy storage means is directly connected to the motor controller, and also the power supply means is directly connected to the motor controller, while the motor controller is connected to a vacuum pump. Usually a vacuum pump comprises fast rotating assembly such as a rotor and several rotor elements connected with the rotor. By the rotor elements a gas is conveyed from a pump inlet to a pump outlet. Upon switching off the vacuum pump, in order to ramp-down the vacuum pump, the power supply means is switched off. Due to inertial forces the rotation elements keep rotating with a rotational velocity. This rotational velocity introduces a current into the windings of the electrical motor. The current is then directed to the energy storage means and stored. While rotational energy of the rotating rotor is stored in the energy storage means, energy is withdrawn from the rotor, thus, the ramp-down time is decreased and deceleration times can be shortened. Hence, cycling times are improved. Wherein the term ramp-down is not limited to a complete deceleration from full rotational speed to zero rotational speed of the rotor but also includes any substantial and at least partial decrease of rotational speed of the rotor.

Preferably the energy stored in the energy storage means is used during ramp-up of the vacuum pump. Thereby, the stored energy of the energy storage means is able to accelerate the ramp-up procedure and thereby decrease the ramp-up times. Preferably the energy stored in the energy storage means is combined with the electrical energy of the power supply means. Thus, upon start-up or ramp-up of the vacuum pump, preferably initiated by a motor controller which is configured to send a start signal to the power supply means in order to initiate the ramp-up of the vacuum pump, the power supply means is switched on in order to ramp-up the vacuum pump and additionally the energy stored in the energy storage means is used to accelerate the ramp-up procedure. As a consequence a smaller power supply means is possible, since additional energy is provided by the energy storage means to enable rapid cycling. The power supply means can thus be chosen to provide less power which is still sufficient for normal operation of the vacuum pump for full speed running, since the most energy consuming part of the pump cycle, i.e. the ramp-up procedure, is supported by the energy storage means. Hence, costs can be reduced due to a smaller power supply means, while cycling times can be improved. Wherein the term ramp--up is not limited to a complete acceleration from zero rotational speed of the rotor to full rotational speed but also includes any substantial and at least partial increase of rotational speed of the rotor.

Preferably the energy in the energy storage means is stored electrically, mechanically, chemically and/or thermally.

Preferably the energy storage means comprises a battery, a capacitor, a pressure vessel or a flywheel to store the energy. In particular, if the energy in the energy storage means is stored mechanically or thermally, a further device is employed in order to convert the stored mechanical or thermal energy into electrical energy which is then combined with the electrical energy of the power supply means.

In one embodiment the electrical energy provided to the vacuum pump is completely generated by the energy storage means. Thus, in the case of power cuts, the pump is able to be operated further. Additionally, the pump can further be operated if the pump is temporarily not connected to the mains power supply. Since operating a vacuum pump at full running speed requires only a smaller power compared to the ramp-up procedure, it is possible to further operate the vacuum pump by the energy stored in the energy storage means at least during temporary disconnection.

Further, the present invention relates to a vacuum pump and in particular to a turbomolecular pump which comprises a stator and a rotor rotated relatively to the stator by an electric motor. The rotor comprises at least one rotor element in order to convey a gas from a pump inlet towards a pump outlet. Further a controller is connected with the electric motor in order to control operation of the vacuum pump. The controller is connected to a power supply system. With the power supply means or the controller an energy storage means is connected, whereby the energy storage means is configured to store energy produced by the vacuum pump during ramp-down of the vacuum pump as previously described.

Preferably the power supply system is built as previously described.

Preferably the energy storage means are built as previously described in conjunction with the power supply system.

The present invention further relates to a method to shut down a vacuum pump wherein the power supply means is switched off and wherein energy produced by the vacuum pump after switching off the power supply means is stored. The energy is produced due to the inertial force of the rotating elements of the vacuum pump which introduces an electric current into the windings of the electric motor. Thereby the rotational energy of the rotating elements is stored by e. g. a energy storage means.

Further, the present invention relates to a method to start-up a vacuum pump, wherein power supply means is switched on and electrical energy of the power supply means is combined with the electrical energy transferred from an energy storage means. Thus, the ramp-up time for the vacuum pump is decreased due to the combined use of the electrical energy of the power supply means and the electrical energy generated by the energy storage means. Thus, the requirements for the power supply means are reduced, while improving cycling times.

Preferably the method to shut down a vacuum pump and/or the method to start-up a vacuum pump make use of the power supply system as previously described and/or the vacuum pump as previously described. Preferably one or both methods comprise features disclosed with respect to the power supply system and/or the vacuum pump.

The Summary is provided to introduce a selection of concepts in a simplified form that are further described in the Detail Description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE FIGURES

Exemplary embodiments of the invention will be explained in detail with reference to the accompanied drawings.

In the Figures:

FIG. 1 shows a vacuum pump with a power supply system in accordance with the present invention during ramp-down procedure,

FIG. 2 shows the same vacuum pump of FIG. 1 during ramp-up procedure and

FIG. 3 shows another embodiment o present invention.

DETAILED DESCRIPTION

The inventive vacuum pump 11 comprises a stator 10 with several stator elements 12, a rotor 14 with several rotor elements 16, whereby the rotor 14 and the rotor elements 16 are rotated relatively to the stator 10. The rotor 14 is driven by an electric motor 18, which is connected via a motor controller 20 with a power supply 22. The motor controller 20 controls operation of the vacuum pump 11, i. e. initiates ramp-down and ramp-up procedures. In the present example the energy storage means is built as battery but different energy storage means can be used analogously. The battery 24 is connected with the power supply 22. In the present example the power supply means is mains electricity but different power supply means, eg a battery or uninterruptable power supply, can be used analogously. If the motor controller 20 initiates a ramp-down procedure, the power supply 22 is switched off. Due to initial force, the rotor 14 and the rotor elements 16 are rotating further. This rotation induces a current into the windings of the electric motor 18, thereby converting the rotational energy of the rotor 14 into electrical energy. The energy produced is then transferred to the battery 24 as indicated by the arrows 26 and stored by the battery 24. Due to the withdrawal of energy from the rotor 14 in form of electrical energy, the ramp-down time is decreased.

During ramp-up or start-up of the vacuum pump 11 (shown in FIG. 2) the motor controller 20 initiates the start-up procedure. Thereby, in FIG. 1 same or similar elements are indicated by the same reference numbers. Upon initiating the vacuum pump start-up the power supply 22 is switched on, as indicated by the arrow 28. In order to decrease the ramp-up time energy stored in the battery 24 is combined with the electrical energy of the power supply 22. The combined energy of the battery 24 and the power supply 22 is then fed to the electrical motor 18, as indicated by the arrows 30, in order to accelerate the rotor elements 16. Thus, the ramp-up time is shortened compared to the ramp-up time with only the power supply 22. Hence, the requirements for the power supply 22 are reduced and a smaller power supply system 22 can be chosen, thereby reducing the costs of the system while enabling short pump cycling times.

Additionally, it would also be possible to operate the vacuum pump 11 completely by the, battery 24, if the power supply 22 is not able to provide electrical energy to the electric motor 18 due to power cuts or if the power supply 22 is temporarily not connected to the mains power supply. This is in particular possible, if the power supply 22 is temporarily disconnected from the mains power supply when the vacuum pump 11 is at full running speed running. If the vacuum pump 11 is at full running speed, only a small amount of power is required in order to maintain the vacuum pump 11 in the operation condition. This amount of power can he completely provided by the battery 24 if the battery is of appropriate capacity.

Hence, by the present invention, energy generated by the vacuum pump 11 during the ramp-down procedure is stored by a power storing means. This stored energy can be used during the ramp-up procedure in addition to the general power supply. Thus, the ramp-down time and also the ramp--up time for the vacuum pump 11 are decreased leading to shorter pump cycles providing the customer with a more convenient handling and an enhanced efficiency by use of the vacuum pump 11 in accordance with the present invention.

FIG. 3 shows another embodiment of the present invention, wherein same or similar elements are indicated by the same reference sign. In contrast to the embodiment of FIGS. 1 and 2, the energy storage means also built as battery 24 is directly connected to the controller, rather than connected to the power supply means. However, the functionality is the same, such that during ramp-down of the vacuum pump 11, rotational energy is transferred to the battery 24 as indicated by arrows 26. The stored energy can be used to accelerate the ramp-up procedure of the vacuum pump 11. Thus, preferably the energy storage means is built separate of the power supply means connected and/or disconnected from the controller independently from whether a power supply means is connected. Replacement of the battery 24 or uses of the vacuum pump without power supply means at least temporarily is possible.

Although elements have been shown or described as separate embodiments above, portions of each embodiment may be combined with all or part of other embodiments described above.

Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are described as example forms of implementing the claims. 

1. A power supply system for a vacuum pump comprising: a power supply means to supply electrical energy to the vacuum pump for operation; and an energy storage means connected to the power supply means or a motor controller to store energy transferred from the vacuum pump during ramp-down of the vacuum pump.
 2. The power supply system according to claim 1, characterized in that energy stored in the energy storage means is used during ramp-up of the vacuum pump.
 3. The power supply system according to claim 1, characterized in that the energy in the energy storage means is stored electrically, mechanically, chemically and/or thermally.
 4. The power supply system according to claim 1, characterized in that the energy storage means comprises a battery, a capacitor, a pressure vessel, a fuel cell or a flywheel.
 5. The power supply system according to claim 1, characterized in that the electrical energy provided to the vacuum pump is completely supplied by the energy storage means.
 6. A turbomolecular pump, comprising: a stator; a rotating assembly rotated relatively to the stator by an electric motor, wherein the rotating assembly comprises at least one rotor element in order to convey a gas from a pump inlet towards a pump outlet; a controller connected to the electric motor; and a power supply system connected with the controller; characterized by an energy storage means connected either to the power supply system or the controller to store energy transferred from the vacuum pump during ramp-down of the vacuum pump.
 7. A method for shutting-down a vacuum pump, wherein a power supply means is switched off and energy produced by the vacuum pump after switching of the power supply means is stored in energy storage means.
 8. The method of claim 7 further comprising starting-up the vacuum pump, wherein the power supply means is switched on and electrical energy of the power supply means is combined with energy generated by the energy storage means.
 9. (canceled) 